In the production of non-polluting motor vehicles wherein electric drives replace the internal combustion engine high energy density batteries of the secondary type have been employed to drive a main electric motor or individual electric motors powering the wheels of the vehicles. Such high energy density (HED) batteries are those which are capable of generating at least 50 watt-hours per pound. Among these, one which shows great promise for commercial acceptance is based on metal and halogen electrodes in an aqueous electrolyte of the metal halide. Particularly useful is such a system wherein the negative terminal is connected to zinc or other suitable metal electrodes of a plurality of cells and the positive terminal is connected to "chlorine electrodes" which preferably are created by bringing gaseous chlorine, dissolved or dispersed in aqueous metal chloride electrolyte into contact with an inert conductive electrode, such as through openings in an inert electrode, such as one of porous carbon or graphite.
In metal-halogen HED batteries suitable for motor vehicles a convenient source of halogen is needed and, as described in U.S. Pat. No. 3,713,888 halogen hydrates are convenient sources of halogens and chlorine hydrate is especially suitable for use in furnishing chlorine to the electrolyte as feed for the chlorine electrodes of the present batteries. The halogen hydrates of chlorine and bromine are normally solids. It is believed that chlorine hydrate should be given the formula Cl.sub.2.6H.sub.2 O, which may be maintained in the solid state at temperature below 9.degree. C. and atmospheric pressure, and preferably in the range of -50.degree. to +5.degree. C. The chlorine may be supplied to the HED batteries by addition of halogen hydrate to circulating electrolyte during the period in which the battery is discharging and such supply may be effected by physical addition of the hydrate or by thermal decompositions thereof and feeding of the products chlorine and water to the electrolyte. The hydrate may be manufactured in conjunction with the operation of the motor vehicle or may be produced in a larger installation from which it may be supplied to motorists in need of "refueling". In either case, improved apparatuses and processes for the manufacture of the hydrates have been needed.
In the past several such apparatuses and methods have been invented by researchers working for the present assignee. These are the subjects of U.S. patent application, Ser. No. 257,114, filed July 5, 1972, entitled, Apparatus and Method for Producing Halogen Hydrate; Ser. No. 200,047, filed Nov. 18, 1971 for Manufacture of Chlorine Hydrate; and Ser. No. 200,046, filed Nov. 18, 1971 for Apparatus and Method for Making Chlorine Hydrate from High Energy Density Battery Electrolyte and Chlorine. In the methods described in those applications the aqueous medium employed with the halogen was in a continuous liquid state, obtained from a pool of liquid, or was condensed from water vapor. Although the methods described therein are practicable, additional advantages and improved production rates are found to result from the use of the aqueous medium in the particular form described in this invention and by utilizing the other conditions and apparatuses thereof.